"SAN PEDRO, Calif. -- If there's a computer on your desk, a Sony television in your den or a pair of Nike sneakers on your feet, you're connected to Pier 400 at the Port of Los Angeles here."

"Sprawling nearly 500 acres and dotted with 10-story blue cranes, the pier is the hub of the biggest U.S. port -- and the generator of some of the nation's worst air pollution from ships, trucks and trains lugging containers stuffed with electronics, furniture, clothes and cars.

A decade ago, diesel exhaust swathed the port and neighborhoods just outside its fence in a deadly blanket of soot. Regulators calculated that the port's neighbors faced cancer risks so high that physicians dubbed the area the "diesel death zone.""